This invention relates to a multi-function switch of the type that is commonly mounted on the steering column of an automotive vehicle to perform various control functions that are in addition to the usual right and left turn signals given by the switch.
For various reasons it has become desirable to incorporate additional switch functions into what is commonly called the turn signal switch. For example, speed control, windshield washer and wiper control, and headlamp dimmer control are common examples of such additional functions. In embodying these additional functions into a turn signal switch, it is desirable that the basic turn signal operation that has become more or less standard through many years of usage be retained because of its widespread acceptance.
Virtually all turn signal switches comprise a body on which an actuating lever is pivotally mounted. The switch body is disposed on the steering column, either internally or externally, such that the lever projects away from the column generally to the left. When a turn is to be made, the lever is pivoted in the direction of turning to a position where it remains latched until after the turn has been completed at which time it is cancelled to return to its original position.
Typical turn signal switches embody cancellation mechanisms that automatically cancel the turn signal after a turn has been completed. However, steering motions to accomplish a turn do not necessarily always involve a consistent turning of the steering wheel in the direction of turning as the turn is being made. For example, a large highway tractor/trailer combination that must make a comparatively sharp turn (such as a right turn around a corner) is often initially steered somewhat in the opposite sense as the turn is approached (i.e., somewhat to the left) so that a large enough turning radius for the combination can be attained to allow the trailing end of the combination to clear the corner as the turn is being completed. Hence, automatic turn signal cancellation mechanisms that cancel upon the mechanical sensing of a small amount of motion opposite to the intended direction of turning are usually unsuitable for highway trucks because they could be prone to producing premature cancellation.
One aspect of the present invention relates to a new and improved organization and arrangement for a turn signal switch which renders the switch well suited for highway truck usage, particularly insofar as the automatic cancellation function is concerned. Specifically, this aspect of the invention relates to a novel cancellation mechanism in which the cancellation is performed by means of an electromagnetic cancellation mechanism that is operated from turning and speed information that is transmitted to a microcomputer by appropriate sensors. The microcomputer can process the turning and speed information in such a way that premature cancellation will be avoided for most types of turning. Similarly, the information to the microcomputer can be used to allow the turn signal to perform a lane change inication by detecting conditions indicative of the execution and completion of a lane change, and then cancelling. Furthermore, an inadvertent turn signal of which the vehicle operator may be unaware will be cancelled by detecting steering and driving conditions that are inconsistent with the execution of either a lane change or a turn, such as after the lever has been pivoted on for a certain amount of time while the vehicle is being driven in a generally straight line along a street or highway or after the vehicle has accelerated to a certain speed.
U S. Patents that are representative of known turn signal cancellation mechanisms are: U.S. Pat. Nos. 4,058,797; 4,128,770; 4,213,116; 4,302,748; 4,306,218; 4,333,071; 4,357,507; 4,358,751; 4,638,290; and 4,648,728. Headlamp switch cancellation mechanisms are shown in U.S. Pat. Nos. 3,373,312 and 4,577,117.
A further feature of the invention relates to the organization and arrangement of the turn signal lever on the switch body and more particularly to the manner in which the cancellation mechanism interacts with the lever to maintain the lever in turn signalling position during a turn until such time as the turn signal is to be cancelled upon completion of the turn. Of course a turn signal may be cancelled manually at any time simply by pivoting the lever back to its normal off position
A unique organization and arrangement of the lever and cancellation mechanism endows the switch with the capability for the lever to give additional signals for other functions, either at the same time that it is giving a turn signal, or at any time when it is not giving a turn signal. In the disclosed embodiment of the invention, the turn signal lever is, in addition to being able to give right and left turn signal commands, also pivotable in opposite directions transverse to the directions of giving the right and left turn signals. The headlamp hi-beam/lo-beam selector switch (commonly known as a dimmer switch) is operated when the lever is pivoted in the first of these other directions and the marker lamps are interrupted to provide a marker interrupt signal when the lever is pivoted in the second of these other directions. Hence, headlamp dimmer control and marker interrupt signalling are the two additional functions that can be performed by the lever, not only when the turn signals are off, but also even when a turn signal is being given.
Furthermore, the lever can also be displaced longitudinally of the switch body to perform additional switching functions. When the lever is pulled outwardly, the hazard warning function is given. After the lever has been pushed inwardly to terminate the hazard warning function, a still further inward pushing will be effective to operate the windshield washer pump motor to cause washer fluid to be dispensed onto the vehicle's windshield.
One of the constructional features of the switch is a ball and socket type joint that is used to pivotally mount the lever on the switch body. Such a construction can be economically fabricated, and it occupies a comparatively small amount of space, especially when compared to prior multi-function turn signal switches that often employ plural gimballed joints, or the like, in order to attain four directions of pivotal motion for their levers. The socket is formed in a seat member which is itself displacable in two directions axially of the switch body, the first outwardly, when the lever is pulled outwardly. to give the hazard warning signal, and the second inwardly, when the lever is pushed inwardly, to terminate the hazard warning signal. When the lever is pushed still further inwardly to operate the windshield washer pump motor, the ball, which is on the lever, can unseat a limited amount from the socket, returning to seat in the socket after the pushing force on the lever has ceased.
An additional constructional feature is the surface configuration of an axial end face of a piston that houses the cancellation mechanism and that interacts with the lever during its pivoting to give the various signals heretofore mentioned. This face comprises a complex surface configuration and through resilient biasing of the piston is caused to bear against the tip of the lever to maintain the ball forcefully seated in the socket. The piston face has different surface contours that enable the lever to be retained in a turn signalling position until cancelled, yet also enabling the headlamp dimmer and marker lamp interrupt functions to be performed regardless of whether or not a turn signal is being given. When a turn signal is to be automatically cancelled, the electromagnet of the cancellation mechanism is energized to cause a plunger-operated ramp to protrude through a slot in the piston face that bears against the lever tip, to unseat the lever tip from the piston face, and to cam the lever from its pivoted position back to the off position where it is collinear with the switch axis body.
Still another constructional feature of the switch is the disposition of a circular array of individual electrical switches on the interior face of the outer axial end wall of the switch body for selective actuation by a circular disc that is disposed transversely of the lever between the interior axial end of the lever and the ball and socket joint. Positioning of the lever in the manner described above produces a corresponding positioning of the disc, whose peripheral edge activates the appropriate switch or switches of the array, depending upon exactly how the lever is operated.
Examples of prior turn signal switches that illustrate different constructions for the lever mounting, including the gimbal type mounting referred to above, are: U.S. Pat. Nos. 4,006,328; 4,139,749; 4,219,706; 4,293,743; 4,315,117; 4,328,431; 4,352,401; 4,357,507; 4,379,954; 4,543,456; 4,616,224; 4,628,310; and 4,640,997;
Still further switching functions are incorporated into the multi-function switch of the present invention. Additional switch functions are performed by arrays of switches that are disposed on the outside of the switch body and cooperatively associated with rotary actuator elements that are adapted for arcuate motion in the circumferential sense about the axis of the switch body. Although the switch elements of each of these arrays are disposed on the exerior of the switch body, they are covered by the corresponding actuator.
A series of circumferentially extending detents are provided for each rotary actuator whereby discrete settings of each actuator produce unique switch actuation patterns for the switches of the corresponding array. Moreover, limited movement of an actuator to either side of a discrete detent setting is effective to change the status of switches of the array so that further different unique switch signalling patterns are presented to each side of a discrete detent setting. The unique patterns of actuation of the switches in the arrays can be advantageously used for controlling cruise control and windshield wiper motor control functions, the specific examples disclosed herein.
For instance, when an actuator that is used to control the windshield wiper motor is placed at the discrete detent setting corresponding to an intermittent wipe mode of operation, the motor will operate in the intermittent mode. If it is desired to increase the wipe delay, the switch is rocked to one side of the detent setting, and the change in status of the switch pattern of the array is detected by the microcomputer which makes an adjustment in the amount of the delay depending upon the time for which the actuator is held rocked away from the detent position. Similarly, a decrease in delay is accomplished by rocking in the opposite direction.
The invention is advantageously configured for the use of membrane type switches for the arrays that are associated not just with the rotary actuators, but with the lever too. The membrane switches are quite thin and can be mounted on surfaces of the switch body without occupying a large volume of space. While it would be possible to press directly on such a membrane switch and operate it, the thinness of the membrane switches with their extremely limited amount of switch travel might seem too precise for mass production fabrication and assembly operations of the tolerances typically used for automotive-type switches.
The multi-function switch of this invention admirably addresses this concern by utilizing resiliently compressible actuator pads disposed in association with the membrane switches such that each switch is actuated through a corresponding pad. Each pad is effective to operate the corresponding membrane switch in response to pressure applied to the pad while absorbing a certain amount of the actuator travel whereby close tolerancing of the actuators to the membrane switches is avoided. This makes the switch assembly well suited for automotive mass production procedures using tolerances typically associated with mechanical switches of this general type.
These compressible, resilient pads have one particular configuration for the array of switches that perform the turn signal, headlamp dimmer, marker interrupt, and hazard warning functions, and a different configuration for the arrays of switches that are used with the rotary actuators. Both will be described in detail later on in the specification.
Examples of very thin, or membrane type switches are shown in U.S. Pat. Nos. 4,087,663; 4,131,772; 4,308,439; 4,394,555; and 4,518,836. Other examples of switches associated with automotive vehicle steering columns are found in: U.S. Pat. Nos. 4,180,713 and 4,578,592.
Other parts of the switch are also well suited for economical fabrication and the use of automated assembly procedures. The switch comprises a metal body that can be fabricated using conventional machining procedures. The cancellation mechanism also comprises metal parts that can be conventionally machined.
To then briefly summarize, a switch embodying principles of the present invention is capable of providing a number of switching functions in a comparatively compact volume and in a manner which is conducive to economical mass production fabrication and assembly. The switch carries very low currents through the membrane switches and is especially well-suited for use with a microcomputer that is responsive to the membrane switch conditions for in turn controlling power circuits to the various lamps and other electrical load devices on the vehicle that are under the control of the multi-function switch. It also possesses new and unique functional features which are beneficial for the operator of the vehicle.
The foregoing features, advantages and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a presently preferred embodiment according to the best mode contemplated at the present time in carrying out the invention.